Greetings -

I'm trying to convert Inventor axis,angle rotations to

x-angle,y-angle,z-angle form. Does anyone have an algorithm handy

or know of a good reference?

Mark

Greetings -

I'm trying to convert Inventor axis,angle rotations to

x-angle,y-angle,z-angle form. Does anyone have an algorithm handy

or know of a good reference?

Mark

Graphics Gems IV (or maybe 3 or 2 or 1, but I think it is 4...) has aQuote:> I'm trying to convert Inventor axis,angle rotations to

>x-angle,y-angle,z-angle form. Does anyone have an algorithm handy

>or know of a good reference?

great article on converting quaternions (the representation Inventor

uses) to Euler angles (x-angle, y-angle, z-angle is one particular set

of Euler angles) by Ken Shoemake.

(Don't you just hate people who use too many parentheses)

--

Inventor on the www: http://www.sgi.com/tech/Inventor.html

Quick question dealing with quaternions verse Euler(angles or paramters)...

What are the major advantages/disadvantages to it? We use Euler Parameters

in our routines for dynamics calculations... Is there an advantage graphically

to useing one or the other?

I have very basic knowledge of Eulor and almost none of quaternions(just that

Eulor parameters are normalized quaternions)...

Anyway just curious here... no Biggie

I have a question. What I need is some direction or tips to speed up an

inventor scene(OpenInventor, Indigo r4000 not sure gfx, but not 8-bit).

Here's sort of the basic scene.. Its a SoSeperator with 12 children, 11

of the children are SoShapeKit-Nurbs, and the other is a SoShapeKit-Sphere.

I know NURBS in general(or it sure seems it) are slower than most other forms

but is there any good hints as to ways to speed the rendering up? I'm

animating the scene and need the rendering to be quick. Right now I think I

get somwhere in the area of 1 render per second... I would like 15/sec but

would settle with 5/sec or so... All the nurbs are revolved shapes...(its a

bowling alley basically).

Also, something that always bugs me... Is there a way to make callbacks wait

until the SoXtViewer is done drawiong its window and buttons and such before

it attampts to start animating? I just usually miss the first 5-10 frames

because of this..

Bruce Tennant

Chace and Associates Engineering

Euler paramaters == quaternions used for orientations == unit quaternionsQuote:>Quick question dealing with quaternions verse Euler(angles or paramters)...

>What are the major advantages/disadvantages to it? We use Euler Parameters

>in our routines for dynamics calculations... Is there an advantage graphically

>to useing one or the other?

Euler angles are three independent axes used to specify an orientation

(e.g. yaw-pitch-roll or X-Y-Z).

Quaternions/Euler paramaters are:

-- very easy to convert to a rotation matrix

-- are fairly easy to interpolate

-- never suffer 'gimble lock'

The only advantages I can think of for Euler angles are:

-- they use up less storage (3 floats instead of 4)

-- they match how some users think of orientation

--

Inventor on the www: http://www.sgi.com/tech/Inventor.html

1. Inventor rotations into Euler angles

Hi,

Inventor's SbRotation uses standard quaternion representation. So you can

directly convert it to euler angles by using the standard formulae. For more

details refer to the paper titled "Animating Rotation with Quaternion Curves"

by Ken Shoemake, ACM Siggraph 85.

best

- Ashish

--

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Ashish Kolli, Carnegie Mellon University

WWW : http://www.cs.cmu.edu/afs/cs/user/ashishk/www/self.html

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